May 11 (Bloomberg) -- Philanthropist David Rockefeller Sr. is offering an important 1950 Mark Rothko painting at auction next week. The estimated $40 million or more in proceeds will be given to charity, he said, although he hasn't decided on the beneficiaries.

``There are many good causes to which that large sum could be put,'' Rockefeller, 91, said in an interview Wednesday. ``I certainly expect the proceeds to go to one or more of them.''

Rockefeller bought ``White Center (Yellow, Pink and Lavender on Rose)'' in 1960 for $8,500 and hung it at his office when he was chairman of Chase Manhattan Bank from 1961 to 1981. ``White Center'' was most recently in his office at Rockefeller Center until Sotheby's announced in March that he was putting it up for auction on May 15.

The sharp and agile Rockefeller -- who turns 92 on June 12 -- gave considered answers to questions during a 45-minute interview. He still goes to the office daily at 10 a.m. and leaves at 5 p.m. He exercises at a gym twice a week before work. He sometimes drinks a glass of white wine with lunch.

``I was brought up feeling that art is a very important part of one's life,'' said the soft-spoken Rockefeller, dressed in a gray suit, striped shirt and a well-worn red Charvet tie. ``It's something that I not only enjoy, it's something I can share with others.''

Philanthropic Icon

An icon of the philanthropic world, Rockefeller is sought after for donations and public appearances. He attends galas, dinners and social functions as many as three nights a week.

On Wednesday evening, he was an honorary co-chairman of the Japan Society's centennial gala at the Hilton New York Hotel in Manhattan, where former President Bill Clinton gave the keynote address.

Rockefeller's sale of the nearly 7-foot-high Rothko painting is one of the most anticipated lots of the auction season. Art prices for 20th-century works have risen 61 percent last year and have tripled since 1996, according to Art Market Research's index of the most expensive works for artists such as Warhol, Rothko and de Kooning.

Rothko's works have sold for $30 million on the private market. Sotheby's has valued Rockefeller's Rothko at $40 million, which would be the highest price for a postwar artwork at auction, the company has said. Sotheby's has guaranteed the painting, which means that Rockefeller will receive a mutually agreed upon amount regardless of the sale's outcome.

Ties to MoMA

Rockefeller, who has given away more than $900 million in his lifetime, has made large gifts to the arts and education in recent years. In November, he gave $225 million to the Rockefeller Brothers Fund created by his family to support social, educational and environmental causes.

In 2005, he said he would bequeath $100 million to Rockefeller University in New York, a biomedical research institution in New York founded in 1901 by his father and his grandfather, John D. Rockefeller, and $100 million to the Museum of Modern Art.

Rockefeller has deep ties to MoMA and the art world. His mother, Abby Aldrich Rockefeller, was one of the museum's founders in 1929, and MoMA sits on the site of his birthplace and the family's former home at 10 W. 54th St.

Rockefeller said he had no regrets about setting up a trust with MoMA board member Agnes Gund that paid Director Glenn D. Lowry $5.35 million in addition to his museum compensation between 1995 and 2003. The arrangement was criticized because it wasn't initially reported in the museum's tax filings or to the entire MoMA board.

``We had several lawyers go over it before we did it, and I think clearly there is nothing we did that was in any way illegal,'' Rockefeller said.

`Great Director'

Under the leadership of Lowry, who received about $1.28 million in annual compensation in 2005, MoMA raised $239.1 million in private support that year.

``I think we should have told the members of the board, and we didn't,'' Rockefeller said about the trust. ``Glenn is one of the great museum directors. Even though he's paid a substantial sum, he deserves every bit of it.''

Rockefeller said his art collection consists of a ``few hundred'' pieces, ranging from small prints to furniture that he collected with his wife of 56 years, Margaret, who died in 1996. He said he never had a desire to use his collection to start a museum in his name.

``With MoMA, why would I want a museum?'' Rockefeller said. ``I'm delighted to have people come to the house and see what we have.''

With a career behind him in which he wielded power at the pinnacles of banking, diplomacy and philanthropy, Rockefeller said his greatest achievement is his six children, 10 grandchildren and one great-grandchild.

``If they can learn the important things about life and how to lead it, that would be my greatest contribution, Rockefeller said. ``I have reason to think that they will.''

To contact the reporter on this story: Patrick Cole in New York at pcole3@Bloomberg.net.

Last Updated: May 11, 2007 00:21 EDT